Help please i have a 98 gs400 gold edition and the speedometer and mileage on the instrument cluster work when they want to can someone tell me what could be the issue thanks in advance.

 

Don't know too much about electrical, but the most obvious thing to check first is to see if the plugs are loose. If you don't know how to pull the cluster out, just lower your steering wheel and move it out towards you so you have room. Then grab the cluster in between the circles and pull out. It should just pop right out. Unplug it and set it aside. Then the cluster itself is held in place by 4 screws. To take the cluster out, just pull it out towards you and then maneuver it so that the bottom lifts up as you slide it out. There's a video of Mike Tsai doing this while installing the overlays.

If this doesn't do anything, then maybe someone else can chime in. (probably fuse or something like that)

 

You might have a bad speed sensor. You should get that checked out. Unplug it, clean it, lube it up.

 

The speedo/mileage output on the cluster is done with the ABS ecu, the wheels ABS sensors all feed to the ABS ecu and that ecu then sends the VSS output directly to the Cluster.

Do you have ABS, VSC, or TRC lights on the cluster lit up?

The GS doesn't use speed sensors or engine ecu/trans data for the cluster, it only uses those speed sensors for shifting the transmission.